This invention relates to microwave oscillators and superconductors and more particularly to a temperature sensor in the form of a microwave oscillator including a superconductor element operating below its transition temperature.
Stable microwave and millimeter wave signal sources fabricated via microstrip or planar circuit techniques on substrates are well known and are typically in the form of fixed frequency oscillators. One type of such oscillator comprises what is known as a ring resonator oscillator which exhibits not only relatively good frequency stability, but is simple in its circuit configuration. Moreover, transistor ring resonator oscillators integrate readily into miniature and microminiature integrated circuit technology where gallium arsenide (GaAs) field effect transistors (FET) are typically used. The details of a microstrip ring resonator oscillator are generally shown and disclosed, for example, in U.S. Pat. No. 4,185,252, entitled, "Microstrip Open Ring Resonator Oscillator", and issued to Horst W. A. Gerlach on Jan. 22, 1980. A remote temperature sensor including a ring resonator is also shown and described in U.S. Pat. No. 5,115,210, entitled "Microwave oscillator For Operating As A Remote Temperature Sensor", issued in the names of Adam Rachlin et al on May 19, 1992. The teachings of both of these patents are meant to be incorporated herein by reference.